Gas-firing regenerative furnace



Sept. 5, 1939. I PARKER 2,171,597

GAS-FIRING REGENERATIVE FURNACE Filed Aug. 1, 1955 2 Sheets-Sheet 2 ATTORNEY.

g INVENTOR.

Patented Sept. 5, 1939 UNITED STATES PATENT OFFICE GAS-FIRING REGENERATIVE FURNACE George M. Parker, St. Louis, Mo. Application August 1, 1935, Serial No. 34,149 iz-cmmsy ((1263-52) This invention relates to improvements in gasfiring regenerative furnaces, and more particularly to improved methods and means for utilizing natural gas in industrial furnaces, including those originally constructed and equipped to consume gaseous fuels of low thermal value. This application is related to my copending application Ser, No. 743,573 filed Sept. 11, 1934.

In describing the present invention as relating to the combustion of natural gas, it will be noted that this term has heretofore been soniewhat loosely applied to combustible gases obtained from natural underground reservoirs. It is however equally applicable to gases from other sources,

via, the gases prevalently referred to as still gas" or "refinery gas, and those residue gases obtained incident to the refining of petroleum products; the residue gases obtained from natural gasoline stripping plants; also the so-called bottled gas, being commercial propane, butane or the mixtures of these gases as produced commercially from natural gasoline or petroleum products. Accordingly, it is to be understood that, for purposes of the present description, the

term natural gas is utilized to denote any or all gases from the foregoing sources, either individually or as mixtures. More specifically the term may be and is herein used to denote any combustible hydrocarbon or mixture thereof existing in the gaseous phase at 60 degrees F. and 30" of calorific value, in spite of the fact that many or most of the furnaces of the type herein referred to were originallyibnstructed for utilizing gases of much lower thermal value. As typifying the type of furnace here under discussion there is mentioned open hearth furnaces, glass melting tanks, soaking pits, roasting furnaces, skelp furnaces and zinc retort furnaces, or in fact, any furnace constructed to operate on the regenerative principle.

By 'way of preliminary explanation, it may be I notedthat natural gases are characterized by a thermal value of the order of 800 to 3400 British thermal units per cubic foot. Such gases are comparatively fast burning fuels, and are characterjzed by a high flame temperature. However their flame is usually characterized by a low radiant-energy emissivity factor, from which it results that eifective heating within the working zone of a furnace musttake place to a great extent by convectign. In many furnaces of regenerative type, these characteristics of natural gas place it at a distinct disadvantage to other fuels, unless the furnacecan be substantially redesigned and rebuilt, while inmany cases it is entirely unsuitable when fired in the prevalent manner.

The present invention involves a method of firing furnaces of regenerative type havingv separate air and gas regenerators, or at least separate regeneratively heated passages for the air and gas. This firing is effected according to such a process or cycle that a substantial part of the natural gas is reformed into a fuel of substantially low calorific value, and one which is characterized by slightly lower flame temperature. The fiame is however characterized by quantities of finely divided incandescent free carbon, and so' possesses a much higher factor. of radiant energy emissivity. I

A further object of the invention is attained in a method of and apparatus for producing, from natural gas, areformed combustible closely resembling producer gas, so that the natural product may be substituted for and replace existing producer gas equipment without any extensive changes in furnace design; thus in case of interruption of the natural gassupply, producer gas may be substituted without changesin or interruption of furnace operation, since either gas, or

mixtures of the two gases in any proportion may be used with identical results.

-Still a further object of the invention is attained in an improved reformation and combustion of natural gases involving preheating of the gas within a temperature range of 1700-2200 F., whereby there is objectively attained a higher ratio of hydrogen to carbon monoxide, than with any process of reforming natural gases which-has come to my attention.

A still further major object of the invention is attained in the production of a luminous flame in the furnace, due to the presence therein of a quantity of finely divided carbon which becomes incandescent during combustion and the method of controlling the radiance or luminosity of the flame by regulation of the amount of free carbon produced and burned, which is determined by the regulation of the temperature at which the system is operated, with or without a regulation of the amount of steam introduced into the combustible mixture prior to burning, it being however understood that the use of steam is optional,

and does not of itself goto the essence of the presently disclosed technique.

By way of further elaboration 'of certain of the objects above set forth, it may be noted that the present invention distinguishes from the prevalent method of firing gas furnaces with natural gas; in that all or a substantial part of the natcertain of the chambers.

ural gas is or may be transformed, within the regenerative zones of the furnace, to a fuel having the properties above noted, before such fuel is conducted to the burners or working zone of the furnace.

The foregoing and numerous other objects will be fully apparent from the following specification of the invention considered in connection with the accompanying drawings, in which:

Fig. l is a vertical sectional elevation, somewhat of a diagrammatic character, showing the apparatus involved in an application of the invention. to a typical regenerative furnace embodying separate air and gas regenerative chambers, the piping and control elements shown being somewhat enlarged for clearness; Fig. 2 is a view similar to Fig. l, of an application of the principles of the invention to a regenerative furnace of a type, such as an oil-fired furnace, in which only air is regenerated, and in which, according to practice heretofore prevailing, an oil or gas fuel is added at or near the'burners, and Fig. 3 is a horizontal section through one of the regenerators showing the relation of one or more refractory chimneys each involving a separate reaction chamber for the gas, located within the air regenerative chamber, Fig. 3 being taken along line 3-3 of Fig. 2. a I

Referring now by characters of reference to the structure shown by the accompanying drawings, there is indicated at 5 a conduit directed from a suitable source of supply of natural gas such as a receiver or main (not shown). The pipe 5 is connected to a vertical header or riser 6, to which are connected branch pipes containing valves 88 and respectively directed to a gas ignition burner which is optional and may or may not be installed, depending on speciflc conditions, at each side of the furnace and designated at 9 and 9. The gas supply conduits 5-6 terminate in a branched manifold or header llll", the branches of which are providedrespectively with valves II and ll' beyond which the manifold or header is directed through pipes |2-l2' into the gas passages l3 and I3.

The opposite end of the riser 6 is provided with a valve controlling the delivery of natural gas to an air-gas mixing device l5. One end of the mixer is supplied through a pipe or .tube l6 controlled by valve l1, and communicating with an air blower H! which is suggested to be of centrifugal type, and is in turn supplied by air through an inlet pipe IS. The air supply conduit 16 continues beyond the mixer I into a riser 20 communicating in turn with a pair of air-gas supply conduits 2| and 2|, each provided with a valve 22 or 22, each of such branches being directed into one of the opposite gas regenerator chambers 23 or .23. The

latter communicate respectively with the gas delivery passages l3--I3' leading to the burners 24-44 where the gases come in contact with heated air from one of the regenerators 2'|2l' and final combustion begins.

More or less in keeping with conventional construction, the air added to the gas emitted by passages I3-|3'- is augmented by an air supply introduced through air passages 26-26 communicating respectively with or supplied from the air regenerative chambers 21 and 21.

For purpose of augmenting the heat storage and transfer effect of the several regenerative chambers, loosely piled refractory units or checker work 28 may be employed in each or Although the introduction of steam with the air-gas mixture is to be understood as by no means essential to the processes and methods herein disclosed, under certain conditions its use is advantageous in controlling the character, particularly the luminosity of the flame of final combustion, due to its influence on the formation of free carbon. When steam is desired, it is my preference to utilize a steam supply line 29 controlled by a valve 30 equipped with a flow meter 3| and conveniently directed into the airgas header 20.

The features of construction'of regenerative furnaces are generally known and thought to require no extended description beyondthat incident to the apparatus utilized in the practice of v the presently improved process or method. The furnace may conveniently be of the so-called Siemens type in which the corresponding'regenerative chambers are selectively and alternately connected, as by dampers, to the chimneys, the fur-' nace being so utilized that the hot gases therefrom, during a given direction or cycle of combustion, pass through and heat two ofthe checker works, e. g., those in chambers 23 and 21. When these are sufficiently heated the flow of furnace gases is reversed, being turned through Chambers 23' and 21' through which they now pass to the chimney. In this manner, byalter= nately throwing a given pair of the chambers into the inlet and into the discharge end of the furnace, the air and gas for combustion are always introduced through heated checker work, and thus their temperature is muchhigher than if introduced cold. It will, of course, be understood as my preference that in keeping with this practice, the working zone of the furnace as well as the gas and air passages are constructed of. or lined throughout with refractory material;

- The modified form of the furnace illustrated by Figs. 2 and 3 involves the utilization of the same efficient method of reforming gas and of firing as does the showing of Fig. 1, being herein included to illustrate an application of the improved method and process to furnaces of types originally fired with oil or natural gas, and in which only the air is regenerated, the oil or 'gas fuel being originally added at or near the burners. The modification of Fig. 2 involves a refractory chimney or chimneys, or a separate reaction chamber for the gas, located within the air regenerative chamber for the purpose of effecting a partial combustion of the air-natural gas mixture with a controlled restricted amount of air while passin through the heated air regenerative chamber. In

' the modified form of furnace the natural gas supply (not shown) isconnected to a header 35, shown as a riser pipe terminating upwardly in supply branches 36-36, provided respectively with valves 3'1v and 31' and directed into the gas supply chimneys 38 and 38'. These are directed to the burners 39 and 39 located within or adjacent to the combustion zone 40 of the furnace. The riser 35 is provided also with intermediate branches 4 l--4.l valved as at 42 and 42', connected respectively with ignition burners 43 and 43'. The ignition burners serve, as desired, to bring the checkerthe: regenerative. heating of the checkerwork,

which is usually adequate, may fail for any reason, the ignition burners may be utilized to aid in heating and maintaining the heat of the checker-- work. Further, in case of inadequate regenerative heating of the checkerwork, the ignition burners may be utilized to maintain the proper temperature range within the lower regions of the reforming chambers, in a manner to offset the gradual cooling effects due to incoming raw gas or air, or mixtures thereof.

.An additional branch 44 is provided with a valve 45 and serves to convey gas to the gas-air mixing device 46 which may correspond to the mixer l5 of Fig.1. The mixer of Fig. 2 is located in the air supply pipe ll, provided with branches 41 and 41' and valves "-48 respectively, the conduit 41-41 being directed each into the lower or inlet end of one of the gas chimneys it or 38', and are supplied from the common air conduit 50. The air supply, according to the showing of Fig. 2, is not pressure-fed as by the blower l8 of Fig. 1, although it may optionally be so equipped. In many cases it has been found that, provided the conduits 41, 41' and El are of suflicient size, a natural draft is sumclent to supply more than the requisite flow of air, as in some cases the kinetic energy of the gas under pressure may be utilized to inspirate the desired quantity of air. For the purpose of supplying steam where desired, a supply line therefor is designated at 5i," provided with a valve 52 and a flow meter 53, the function of these parts being substantially the same as the corresponding elements heretofore discussed.

In the furnace according to Fig. 2, each of the opposite regenerative chambers in effect consists of a single chambered structure Si or I, optionally provided with the checker work Il"', in Fig. 3 the checker work being omitted for cleamess, this transverse sectional elevation serv-' ing to show a preferred arrangement of furnace in which five burners are employed at each side, and accordingly in which there will be provided five of the flue passages or chimneys 2. for the delivery of reformed gas anda restricted amount of air to the burners. As in Fig. 1, the entire structure is preferably formed of or lined with refractory materials.

In operation of the apparatus illustrated by Fig. 1, the raw natural gas is supplied through the conduit 5 and valve H to the mixing device ll, air being supplied thereto by the blower IO, w th the air and gas in predetermined ratio, and the airgas mixture being delivered to the conduit 20. While the gas supplied to the-reforming chambers such as 23 or 23', 28 or 2|,is referred to as an a rgas mixture, it should be understood that'the gas so introduced may consist substantially or entirely of raw natural gas. According to preference, the usual practice in case some air is added, is to introduce the air in a ratio varying from substantially two and one-half (2%) volumes of air to one 1) volume of natural gas, to substantially five (5) volumes of air to one (1) volume of natural gas. When any substantial proportion of air is introduced, the purpose of its addition is to supply some, but a deficient quantity of oxygen for purposes of partial combustion, so that the partial burning of the gas supplies heat for the reformation of the remainder. If, however, a

and gas enters the chambers such as 23, part of the natural gas, say of substantially onethousand B. t. uv heating value, is burned by the air, while the balance of the gas is reformed into gases of substantially lower thermal value with the formation of some carbon. If it be desired that a part or all of this carbon be burned by air,-

the ratio of air to gas is preferably substantially 4:1. If on the other hand it is desired to obtain a blue water gas effect by utilization of this carbon, the volumetric ratio of air to gas is preferably about 2 :1, in this case the by-product carbon being caused to combine with the proper amount of steam introduced as hereinafter described;

From the foregoing it will appear that the actual ratio of air to gas may be varied between 0:1 and 5:1, depending upon the nature of the flame and thermal characteristics desired in the gas delivered to the working zone of the furnace for final combustion. 1

When desired, steam may be added through the pipe 29 in a predetermined amount indicated by the flow meter Ii. From this point the mixture is conducted to one of the headers 2| or 2i, under control of the valves 22-22, whence it is discharged into one of the gas regenerative and gas reforming chambers 23 or 22'. It may here he noted that while the valves 22-22' are shown as of globe or gate type, valves of the butterfly type may be employed in lieu thereof, and if desired, may be so interconnected that opening either compels the closure of the other thereof; alternately, a single two-way valve may be employed at this point, or any other of the usual equivalents utilized for control purposes. Within the selected chamber 2! or 22', the amount of air being substantially deficient for complete combustion of the gas, only a partial combustion takes place, with some cracking or decomposition, and the resultant products thereof pass through one of the conduits I! or l2, to the associated burners. At the burner, preheated air is supplied from one of the air regenerative chambers 21-21 through the conduit 28 or 2|- and final and complete combustion takes place within the working zone 25 of the furnace. As may be dictated by thermal requirements of the furnace, raw or unreformed natural gas may be introduced through one of. the conduits l2 or l2 under control of valves II or Ii and thus mixed with the gas in the associated conduit I! or II" before it reaches the burner. It is preferred that the basic temperature requirements of the furnace be met my the reformed gas, and that if and when required, the B. t. u. of the gas at the burners be augmented by the supply from one of the conduits l2 or i2.

For the purpose of heating the checker work to the ignition temperature of the air-gas mixture, as on starting a cold 'fumace, the burners 9 or 9' may be utilized, and that, although not usually necessary, these burners may be utilized to maintain the desired temperature of the checkerwork in chambers 23 or 23'; and act as pilots to ignite the incoming air-gas mixture. Since the furnace is reversible, it will appear obvious that,

while the valves designated by prime suffix numerals are open, the corresponding designated" valves on the other side of the control system are closed and vice versa; an exception may however be made in the case of the-valves 8-8 control-' ling the burners 9,- 9, .infjcase these are employed as pilot biumerawhenwboth of the valves: 88' may be allowed-to remain open so thatthe pilots may burn without interruption.

In utilizing the apparatus of Figs. 2 and 3, the practice is sufficiently similar to that in connection with Fig. 1 to obviate detailed description.

Selecting the left hand end of the furnace of Fig.

2,.for example, and assuming the checker work in the regenerative chamber 55 to have been preheated to the requisite temperature, the gas supplied through pipes 35-44 via valve 45 to mixer 46 is introduced to the lower portion of chimney 38 where partial or incomplete combustion and gas reformation with decomposition take place.

" Where desired to augment the heat value of the products in passages 38, valve 31 may be opened for the admission of additional amounts of unreformed or raw gas through pipe 36. Steam may be added as indicated heretofore through pipe 5| and the flow thereof indicated by'meter 53. A predetermined and regulated amount of air is of course, when needed, conducted through pipe 50 to the mixer 46,

In utilizing the apparatus heretofore described, by way of example, in carrying out the presently described improved method of firing natural gas, the refractory materials, say in the gas regenerative chamber 23 (Fig. l), are first heated by the burner 9 or in some other suitable manner, until a substantial part of the refractory in the chamber is brought to a temperature above 1700 F., preferably between 1800 and 2200 F. During this stage of preliminary heating the valves are all closed except the gas valve controlling the ignition burner. Upon attaining the desired temperature in chamber 23, the predetermined mixture, consisting'of natural gas and air in insufficient quantity to burn the gas, is fed to the mixer 15 through regulation of valves l4 and II, this mixture being supplied to the chamber 23 in regulated amount by control of the valve 22. Partial combustion of the mixture now takes place within this chamber, and the heat of such partial combustion reacts upon the unburned hydrocarbons in'the natural gas to decompose thermally at least a portion thereof into carbon and hydrogen, or in the case of the higher members of homologous series, into carbon, hydrogen and lower homclogs. The resultant products of the partial combustion and partial thermal decomposition are thence directed into the conduit. l3 where they are'optionally enriched with raw natural gas as through control of valve II. 7 Once the refractory materials are brought to the deis obvious that the air supplied for final and complete combustion at the burners is highly preheated. It will also appear that any excess carbon which has been deposited upon the refractory material within the gas chamber during a half cycle, may be burned out during the small amounts of unaltered natural gas, the proportion of which will vary in accordance with the control of theprocess, Within limits. For example, in the case of methane (CH4) existing in natural gas in substantial amounts, the following reactions may occur:

(a) Complete combustion CH4+2O2 CO2+2H2O ensuing half cycle, 'so that the refractory mate- (b) Partial combustion 2CH4+3O2 2C0+4H2O (0) Thermal decomposition CH4 C-2H2 From the foregoing it will appear that the fuel gas produced from methane, being the principal constituent of natural gas, is a mixture of carbon dioxide, (CO2), water vapor (H2O), carbon monoxide (CO), finely divided free carbon (C), hydrogen (Hz), nitrogen (N2) and methane (CH4). The extent'and amount of free carbon formation, along with the amounts of carbon monoxide and hydrogen, are susceptible to further control by the introduction of steam which serves to enhance the blue water gas eiTect in the gas regenerative chamber: C+H CQ+Hz. In the case of methanethe addition of steam is usually not necessary, but where the pretreated gas contains substantial amounts of the higher members of the parafiin series, such as ethane (C2Hs), propane (Cal-I8) and butane (C4H10), the ratio of carbon to hydrogen becomes greater and the use of steam assumes an increasing importance in controlling the extent of formation of free carbon.

- The reaction attending the thermal decomposition of the constituents of the .raw gas is exemplified in simplest form in the case of methane, CH4 C+2H2, but becomes more complex in respect to the higher members of the series, and may take place in steps as follows:

In the above thermal equations, the resultant CH4 is decomposed to form C+2Hz so that the consequent products of methane decomposition are essentially C+H2.

By way of exemplifying the effect of reformation of the natural gas in accordance with the process herein outlined, comparative analyses of ,thenatural gas are here inserted, being respectively before and after reformation.

- Per cent by volume Methane Ethane 2.4 Unsaturated hydrocarbons (ethylene) 1.1 Carbon dioxide 0.3

Nitrogen 5.6

The gas of the above analysis was ascertained by calorimeter test to possess a gross calorific value of 966.6 B. t. u. per cubic foot. From a gas of the above analysis, a reformed gas was produced having the following analysis:

Per cent by volume Carbon dioxide 3.9

' Oxygen 0.5 Unsaturated. hydrocarbons (ethylene) 0.2

Carbon monoxide 9.5

Hydrogen 18. 6

Methane- 3.1 Nitrogen -1 64. 2

consumption at an output temperature of 1800.

degrees F. For convenience of reference, it may be noted that, in the reformed gas, the volumetric ratio of reformed gas to the input natural product is 5.55 and the volumetric ratio of hydrogen I to carbon monoxide is 1.96 or practically 2:1. It will be understood that the foregoing is inserted only by way of example, since the hydrogen, carbon monoxide and methane contents of 30.

the reformed gas are susceptible to a substantial range of control within the principles of the present invention.

In practice, thermal decomposition rarely takes place quantitatively, but in any event the theory and nature of the decomposition are distinctly within the scope, principles and intendment of the presently improved method and process.

In attempts heretofore made to fire regenerative furnaces with natural gas, both the air and gas checkers are used for the purpose of regenerating orpreheating the air for combustion, the raw gas and air being brought together in the burners and burning rapidly in the working zone of the furnace. Insuch cases the flame temperature is high, and very little, if any, incandescent free carbon is present to radiate heat and render the flame luminous to any substantial degree. .Accordingly, there results a condition prevalently known as a harsh or a brash heat. The transfer of heat is, under these conditions, accomplished principally by convection. A much more desirable condition is obtainable with producer gas, or gas of similar burning characteristics, which gases have a lower flame temperature than natural gas, and in which are present quantities of incandescent free carbon and other. solids which radiate heat away from the flame, causing more heat transfer to take place by radiation and relatively less by convection, than in the burning of natural gas alone. This type of flame characterizing the burning of producer gas is often referred to as a soft or soaking heat. It is to be noted that the practice herein outlined constitutes a method of attaining a soakthe modified structure, is regarded as necessary.

It will have appeared that the present invention, including, besides the novel elements of fuel supply and reforming structure, a method of its utilization in the firing of regenerative furnaces, embodies in essence a process of reforming natural gas to produce, without substantial change in existing fumaceequipment, a gaseous product of a type approximating producer gas, not only as to thermal value, but as totype of flame, viz., a soft flame or soaking heat characterized by high luminosity due to the presence of substantial quantities of free, finely divided carbon. The importance of the technique herein outlined will be appreciated when it is considered that it enables the ready adaptability of substantially all'types of furnace, at a low cost, to firing with natural gas; and permits such furnaces to use either producer gas or natural gas interchangeably, or concurrently in mixtures of any desired proportion and through a range varying between substantially 100% of produced gas to substantially 100% natural gas. Since the gas producer and connections therefrom to the furnace are notof themselves part of the present invention, they are not described or illustrated herein.

It will also have been noted that it is my distinct preference to burn the reformed gas without intermedlate treatment such as scrubbing and cool-. ing, but carrying the hot gas to its place of ultimate consumption so as to realize on the sensible heat of reactions occurring in the gas regenerative chamber. i

I am aware that certain attempts have heretofore been made to reform natural gases by incomplete combustion thereof prior to actual final and complete burning. However, so far as I am aware, none of these prior attempts have resulted in a gas even approximating the characteristics of producer gas, nor have succeeded in producing a flame bearing a substantial quantity of finely divided carbon to attain a soaking heat. Further, as far as is within my knowledge, none of the I prior attempts in this field attain a reformed gas approximating temperature ranges of the order of 1700-2200 degrees F. preferably employed according to the present disclosure, in the reformation and partial thermal decomposition of the ingredients of natural gas. Further, as far as has been determined, none of the previous attempts in this field have resulted in a gas in which the proportion of hydrogen to carbon monoxide scarcely exceeds a one to one ratio, whereas according to normal practice of the improved process herein disclosed, there results a gas in which the volumetric ratio of hydrogen to carbon monoxide approximates two to one.

It will have appeared that the present invention is simple and inexpensive in its application and is extremely flexible in operation, since the amounts of free carbon, hydrocarbons and products of combustion present in the gas delivered to the burners, may be varied over a considerable range since susceptible to a high degree of control.

It will have appeared that the apparatus utilized in carryingoutthe processes and methods described, may vary substantially from those specifically described by way of illustration; also that the method and process may be practiced in different combinations of steps than those herein described, and that accordingly the invention is not to be understood as restricted by the present disclosure, numerous changes being possible withgen substantially preponderating in volume, and

in the full scope and intended spirit of the invention as defined by the appended claims.

I claim:

1. The herein described method of firing a regenerative furnace with natural gas, which consists in introducing to a regenerative chamber, a mixture of gas with an amount of air distinctly less than the theoretical proportion for complete burning of the gas, maintaining a zone in such chamber at a temperature of an order of 1700"- 2200 F. to effect partial decomposition and reformation of the gas, exposing the gas-air mixture to such temperature for a length of time effective to dissociate it into products including hydrogen and carbon monoxide, with the hydroi "also including substantial amounts of free carbon, so that the reformed gas approximates the characteristics of producer gas, maintaining the reformation zone sufliciently free of oxygen and carbon dioxide throughout the process, to'avoid appreciable oxidation of the free carbon resulting from dissociation of the hydrocarbon content of the,naturalgas, adding air at the burner in a quantity suflicient to provide for complete combustion of the reformed gas and free carbon, in passinga portion of the hot gases resulting from complete combustion through an alternate re-- generative chamber, and alternately utilizing a portion of the last said chamber as ahigh temperature zone and therein effecting a continuation of said partial decomposition and reformation of the gas for further fuel supply to the furnace.

2. The method of reforming and burning natural gas in a regenerative type of furnace, which includes the steps of admixing a raw or untreated gas with a relatively small quantity of air under conditions insufficient to permit complete oxidation by combustion of'any substantial proportion of the gas, passing the air-gas mixture through a zone regeneratively heated in the furnace to a temperature of the order of 1700 to 2200 F., and for an effective time and distance of movement to effect at least a partial decomposition and reformation of,,the gas into products including reformed gas, after passing it to the furnace, in

an amount to provide for complete final combustion, utilizing a portion of the heat resulting from final combustion for maintaining the temperature of said reformation zone, and in so proportioning the ar and raw gas in the admixture thereof, and coordinately with the utilization of said heat of final combustion, as to produce a reformed gas of substantially lower thermal value than the raw gas, and having a hydrogen, free carbon and carbon monoxide content, approximating the characteristics of. producer gass 3. The process of producing gas and firing same in a regenerative furnace, involving the use of natural gas as the raw material, which consists in regeneratively heating a heat transfer medium to a temperature between 1700 and 2200 F., conducting a mixture of natural'gas and air through the zone of said medium and into contact there- ,of hydrogen, carbon monoxide and free carbon,

with the volume of hydrogen materially in excess of that of the carbon monoxide, maintaining the reformation zone throughout the process free of any substantial proportions of carbon dioxide and oxygen, whereby to avoid any oxidation of the greater part of the free carbon resulting from dissociation of the hydrocarbons of the natural gas, the process further; including a continuous removal of the resultant reformed gaseous product from the region of the transfer medium and delivery of the product to a zone of final burning. 4. The process of making and burning a gas of low thermal value in a regenerative furnace, utilizing natural gas as a source of raw fuel, which consists in cracking the natural gas by passage thereof through a regeneratively heated conduit portion of the furnace, at a temperature of the order of HOG-2200 F. and for a length of travel or time to form a basic gas having a lower ther"- mal value than the raw natural gas and including as constituents, a substantial proportion of free carbon, carbon monoxide in a proportion by volume of the order of 10%, and a proportion of hydrogen of the order of 20% by volume, admitting air to the gas during such passage, in a proportion restricted so as to effect dissociation, while avoiding complete combustion to the stage of carbon dioxide, of any substantial proportion of the raw gas, excluding from the cracking regions, throughout the process, any substantial proportion of carbon dioxide, thereafter effecting controlled introduction of natural gas for mixture with said basic gas to vary the composition and thermal value of the final product, thence continuously conducting the final product to the working zone of the furnace, and therein supplymg preheated air in an amount sufficient for complete combustion of the gases.

5. The described method of firing a regenerative type of furnace with natural gas, which consists in mixing said gas with air in a quantity not more than a. distinctly minor part of that theoretically required for complete combustion,

in passing the mixture through a body of refractory material, heating such material to a temperature of the order of 1700-2200 F. prior to its exposure tdthe natural gas-air mixture,

by regenerative action of the stack gases of the furnace, controlling the extent of such heating coordinately with the proportion of admixed air to cause the refractory materials substantially to exceed the ignition temperature of said gas, and to decompose the gas into products including substantial proportions of carbon monoxide, hydrogen and free carbon, with the hydrogen very substantially exceeding the volume of carbon monoxide, maintaining the heating and consequent reformation'action to an extentto effect substantially complete dissociation of the hydrocarbon content, excluding throughout the reformation,

any substantial proportion of stack gas or carbon dioxide, thence conducting the resultant products of such partial combustion, while in heated conditi0n, to the combustion zone of the furnace,

, and in the region of such zone, adding a quantity of air suflicient to promote final and complete combustion.

6. The described method'of firing a regenerative type of furnace with natural gas, which consists in admixing the raw natural gas with steam, and with air in a quantity representing not more than a distinctly minor part of that required to support complete combustion of all of the gas,'

and insufiicient to effect complete oxidation of any substantial proportion of the raw natural gas, regeneratively heating a reaction chamber in a stack gas circuit of the furnace, controlling the extent of such regenerative heating so that such chamber attains a temperature of the order of 1700 to 2200 F., so. as to cause, by reason of oxygen deficiency in said chamber, only partial combustion, but extensive chemical decomposition of the hydrocarbon content of the raw gas into its elements, so maintaining such time-temperature and oxygen-deficient conditions throughout the gas treatment as to result in a gas high in carbon monoxide, hydrogen and free carbon, in which the hydrogen materially exceeds in volume, that of the carbon monoxide, and in conducting the resultant products of the chemical reaction and partial combustion including relatively large amounts of free suspended carbon while still in highly heated condition, to the zone of final combustion in the furnace, excluding from the reaction zones throughout the gas treatment, any substantial proportion of carbon dioxide, and introducing to the final combustion zone a quantity of preheated air sufiicient for final and complete combustion of the ga'seousfuel within the working zone of the furnace.

7. The described method of firing a regenerative furnace, utilizing natural gas and producer gas in selective proportions, which consists in reforming the selected proportion of natural gas in a regenerative zone of the furnace by heatin the gas in such zone to a temperature at least of the order of WOO-2200 F. and in the presence of distinctly a minor proportion of the air which r would be required for complete oxidation of the carbon content of the gas, and in maintaining the gas sufficiently free of atmospheric or other oxygen and'within the saidrange 'of temperatures so as to produce a gas having substantially the characteristics of producer gas, and in which the hydrocarbons are substantially dissociated into their elements including large amounts of finely divided free carbon, but containing carbon monoxide in a proportion of the order of ten percent by volumegin delivering the producer and reformed naturaLgases in the selected proportion to the working zone of the furnace for final combustion therein, 'and'therein supplying air in an amount for complete combustion.

8. The method of reforming natural gasin a regenerative furnace, which consists in introducing the raw natural gas to a reformation zone 9. The method of reforming and burning natural gas in a regenerative furnace, which consists in introducing the raw natural gas to a reformation zone in one of the regenerative fiow circuits of the furnace, excluding any substantial amount of air from such zone during the period of gas reformation therein, and in regeneratively heating said zone alternately with periods of gas reformation, to an extent sufiicient to maintain therein a temperature of the order 'of HOG-2200 F. so as to effect, Without combustion of any material portion of the natural gas to CO2, substantially complete dissociation or decomposition of substantially the greater part of the hydrocarbon content of the gas into its elements, and in maintaining said temperature and preventing access of any substantial amount of air prior to utilization of the gas whereby to maintain a major part of its hydrogen and free carbon in elemental form, in continuing the dissociation of the hydrocarbon of the raw gas to an extent to result in a gas whose constituents approximate those of producer gas and because of a high free carbon content is combustible with a soft flame, and thereafter passing the reformed gas to a zone of final combustion in the furnace, and therein supplying air for complete combustion.

10. The method of firing a regenerative furnace with natural gas consisting in preliminarily heating a heat-transfer medium in a regenerative chamber to from 1700-2200 F., then internally heating said medium and simultaneously conducting natural gas and air into the chamber and into contact with the heat-transfer medium, the ratio of gas to air being such as to effect the burning of part of the natural gas by the air and the reforming of the balance of the natural gas and with the formation of final products of a B. t. u. heating value corresponding to that of producergas, adding preheated air to said final products, burning the resulting mixture in the.

furnace laboratory and discharging waste gases from the laboratory into a regenerative chamber. 11. The method of firing a regenerative furnace with hydrocarbon gas of high calorific value consisting in, preliminarily. heating a regenerative chamber reaction zone adapted to store and transfer heat to from 1700 to 2200 F; then internally heating said zone and simultaneously conducting hydrocarbon gas of high calorific value and air into said zone, the ratio of gas to air biaing such as to effect the burning of part of the gas by the air and the reforming of the balance of the gas and with the formation of final products of a calorific value corresponding to that of producer gas, adding preheated air to said final products, burning the resultant mixture in the furnace laboratory and discharging waste gases from the laboratory into a regenerative chamber reaction zone.

- 12. The process of making and burning a gas of low thermal value in a regenerative furnace,-

utilizing a hydrocarbon gas of high calorific value as a source of raw fuel, which consists in cracking the gas of high calorific value by passage thereof through a regeneratively heated conduit portion of the furnace, at a temperature of the order of 1700 to 2200 F. and for a length of time or travel to form a basic gas having a low thermal value as compared with that of said raw fuel and including as constituents, asubstantial proportion of free carbon, carbon monoxide in a proportion by volume of the order of ten per cent, and a proportion of hydrogen of the order of twenty per cent by volume, admitting air to the gas during such passage in a proportion restricted so as to effect dissociation while avoiding complete combustion to the stage of duction oi gas of high calorific value for mixture with said basic gas to vary the composition and thermal value of the final product, continuously conducting said final product to the working zone of the furnace, and therein supplying preheated air in an amount sufficient for complete com bustion of said final product.

- c GEORGE M.'PARKER. 

